Contrasting mechanisms of proteomic nitrogen thrift in Prochlorococcus

Organisms limited by carbon, nitrogen or sulphur can reduce protein production costs by transitions to less costly amino acids, or by reducing protein expression. These alternative mechanisms of nutrient thrift might respond differently to selection, but this possibility remains untested. We hypothesized that relatively invariant sequence composition responds to long-term variation in nutrient concentrations, whereas dynamic expression profiles vary with nutrient predictability. Prolonged nutrient scarcity favours proteome-wide nutrient reduction. Under stable, nonfluctuating nutrient availability, reduction of nutrient content typically occurs in proteins upregulated when nutrient availability is low, e.g. assimilation and catabolism. We suggest that fluctuating nutrient availability favours mechanisms involving short-term downregulation of nutrient-rich proteins. We analysed protein nitrogen content in six high-light, low-nutrient adapted (HL) vs. six low-light, high-nutrient adapted (LL) Prochlorococcus (marine cyanobacteria) strains, alongside expression data under experimental nitrogen and phosphorus limitation in two strains, MED4 (HL) vs. MIT9313 (LL). HL strains contained less nitrogen, but DNA GC content confounded this relationship. While anabolic and catabolic proteins had normal nitrogen content, most strains showed reduced nitrogen in typical nitrogen stress response proteins. In the experimental data set, though, proteins upregulated under nitrogen limitation were nitrogen-poor only in MIT9313, not MED4. MIT9313 responded similarly to nitrogen and phosphorus limitation, with slow, sustained downregulation of nitrogen-rich ribosomal proteins. In contrast, under nitrogen but not phosphorus limitation, MED4 rapidly downregulated ribosomal proteins. MED4's specific, rapid nitrogen response suggests adaptation to fluctuating conditions, supporting previous work. Thus, we identify contrasting proteomic nitrogen thrift mechanisms within Prochlorococcus consistent with different nutrient regimes.     

Stoichiometric regulation of phytoplankton toxins

Ecological Stoichiometry theory predicts that the production, elemental structure and cellular content of biomolecules should depend on the relative availability of resources and the elemental composition of their producer organism. We review the extent to which carbon‐ and nitrogen‐rich phytoplankton toxins are regulated by nutrient limitation and cellular stoichiometry. Consistent with theory, we show that nitrogen limitation causes a reduction in the cellular quota of nitrogen‐rich toxins, while phosphorus limitation causes an increase in the most nitrogen‐rich paralytic shellfish poisoning toxin. In addition, we show that the cellular content of nitrogen‐rich toxins increases with increasing cellular N : P ratios. Also consistent with theory, limitation by either nitrogen or phosphorus promotes the C‐rich toxin cell quota or toxicity of phytoplankton cells. These observed relationships may assist in predicting and managing toxin‐producing phytoplankton blooms. Such a stoichiometric regulation of toxins is likely not restricted to phytoplankton, and may well apply to carbon‐ and nitrogen‐rich secondary metabolites produced by bacteria, fungi and plants.     

The elemental stoichiometry of aquatic and terrestrial ecosystems and its relationships with organismic lifestyle and ecosystem structure and function: a review and perspectives

C, N and P are three of the most important elements used to build living beings, and their uptake from the environment is consequently essential for all organisms. We have reviewed the available studies on water, soils and organism elemental content ratios (stoichiometry) with the aim of identifying the general links between stoichiometry and the structure and function of organisms and ecosystems, in both aquatic and terrestrial contexts. Oceans have variable C:N:P ratios in coastal areas and a narrow range approximating the Redfield ratio in deep water and inner oceanic areas. Terrestrial ecosystems have a general trend towards an increase in soil and plant N:P ratios from cool and temperate to tropical ecosystems, but with great variation within each climatic area. The C:N:P content ratio (from now on C:N:P ratio) is more constrained in organisms than in the water and soil environments they inhabit. The capacity to adjust this ratio involves several mechanisms, from leaf re-absorption in plants to the control of excretion in animals. Several differences in C:N:P ratios are observed when comparing different taxa and ecosystems. For freshwater ecosystems, the growth rate hypothesis (GRH), which has consistent experimental support, states that low N:P supply determines trophic web structures by favoring organisms with a high growth rate. For terrestrial organisms, however, evidence not yet conclusive on the relevance of the GRH. Recent studies suggest that the N:P ratio could play a role, even in the evolution of the genomes of organisms. Further research is warranted to study the stoichiometry of different trophic levels under different C:N:P environment ratios in long-term ecosystem-scale studies. Other nutrients such as K or Fe should also be taken into account. Further assessment of the GRH requires more studies on the effects of C:N:P ratios on anabolic (growth), catabolic (respiration), storage and/or defensive allocation. Combining elemental stoichiometry with metabolomics and/or genomics should improve our understanding of the coupling of different levels of biological organization, from elemental composition to the structure and evolution of ecosystems, via cellular metabolism and nutrient cycling.     

Optimization of biomass composition explains microbial growth-stoichiometry relationships

Integrating microbial physiology and biomass stoichiometry opens far-reaching possibilities for linking microbial dynamics to ecosystem processes. For example, the growth-rate hypothesis (GRH) predicts positive correlations among growth rate, RNA content, and biomass phosphorus (P) content. Such relationships have been used to infer patterns of microbial activity, resource availability, and nutrient recycling in ecosystems. However, for microorganisms it is unclear under which resource conditions the GRH applies. We developed a model to test whether the response of microbial biomass stoichiometry to variable resource stoichiometry can be explained by a trade-off among cellular components that maximizes growth. The results show mechanistically why the GRH is valid under P limitation but not under N limitation. We also show why variability of growth rate-biomass stoichiometry relationships is lower under P limitation than under N or C limitation. These theoretical results are supported by experimental data on macromolecular composition (RNA, DNA, and protein) and biomass stoichiometry from two different bacteria. In addition, compared to a model with strictly homeostatic biomass, the optimization mechanism we suggest results in increased microbial N and P mineralization during organic-matter decomposition. Therefore, this mechanism may also have important implications for our understanding of nutrient cycling in ecosystems.     

When microbes and consumers determine the limiting nutrient of autotrophs: a theoretical analysis

Ecological stoichiometry postulates that differential nutrient recycling of elements such as nitrogen and phosphorus by consumers can shift the element that limits plant growth. However, this hypothesis has so far considered the effect of consumers, mostly herbivores, out of their food-web context. Microbial decomposers are important components of food webs, and might prove as important as consumers in changing the availability of elements for plants. In this theoretical study, we investigate how decomposers determine the nutrient that limits plants, both by feeding on nutrients and organic carbon released by plants and consumers, and by being fed upon by omnivorous consumers. We show that decomposers can greatly alter the relative availability of nutrients for plants. The type of limiting nutrient promoted by decomposers depends on their own elemental composition and, when applicable, on their ingestion by consumers. Our results highlight the limitations of previous stoichiometric theories of plant nutrient limitation control, which often ignored trophic levels other than plants and herbivores. They also suggest that detrital chains play an important role in determining plant nutrient limitation in many ecosystems.     

Signatures of ecological resource availability in the animal and plant proteomes

Although substantial and ecologically significant differences in elemental composition are well documented for whole organisms, little is known about whether such differences extend to lower levels of biological organization, such as the elemental composition of major molecules. In a proteome-scale investigation of 9 plant genomes and 9 animal genomes, we find that the nitrogen (N) content of plant proteins is lower than that in animal proteins. Furthermore, protein N content declines with the intensity of gene expression for plants, whereas the N content of animal proteins shows no consistent pattern with expression. Additional analyses indicate that the differences in N content between plant and animal proteomes and in plant proteins as a function of gene expression cannot be attributed to protein size, GC content, gene function, or amino acid properties. These patterns suggest that ecophysiological selection has operated to conserve N in plants via decreased reliance on N-rich amino acids. This inference was supported by an analysis of conserved and variable sites indicating that the N content of plant amino acids coded by variable sites is similar to that of the sites conserved between plant and animal genomes and shows no association with expression level. In contrast, in animals, the N content of amino acids coded by variable sites is significantly higher than that for conserved sites, suggesting relaxation of selective constraints for N usage in the animal lineage. This constitutes the first evidence for an influence of environmental resource availability on proteomes of multicellular organisms.     

A preliminary test of catabolic nutrients in explanation of the puzzling treelessness of grassland in mesic Australia

The puzzling exclusion of native trees from grassland under mesic climates can hypothetically be explained by nutritional regimes that make grasses competitively superior to trees. One hypothesis holds that where nutrient concentrations in soils allow catabolism to be as rapid as anabolism at the scale of the whole plant, photosynthates are respired instead of being allocated to stems, resulting in dominance of herbaceous over woody growth‐forms. This matching of catabolic and anabolic rates would depend on the ratios of catabolic to anabolic nutrient elements in soils at a particular site. We consequently investigated elemental concentrations of soils near boundaries between treeless grassland and eucalypt woodland in New South Wales, Australia. Soils were analysed for Be, Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Ba and Pb. Based on our preliminary classification of nutrients as mainly catabolic (e.g. Cu) or mainly anabolic (e.g. Mn), the results showed that, relative to adjacent woodland, the soils under treeless grassland were naturally enriched in anabolic nutrients, but even more so in catabolic nutrients. Furthermore, the greater concentration of Mo – which can induce deficiency of the catabolic nutrient Cu – in soils under woodland than in soils under treeless grassland suggests that catabolic dystrophy allows eucalypt seedlings to prevail in competition with grasses. The results support the theory that where ratios of catabolic to anabolic nutrients are sufficient grasses will achieve competitive superiority over woody seedlings. Our study indicates that soil nutrient concentrations may partly explain the incidence of natural patches of treeless grassland in Australian landscapes otherwise dominated by woody plants.     

Foliar nutrient resorption patterns of four functional plants along a precipitation gradient on the Tibetan Changtang Plateau

Nutrient resorption from senesced leaves as a nutrient conservation strategy is important for plants to adapt to nutrient deficiency, particularly in alpine and arid environment. However, the leaf nutrient resorption patterns of different functional plants across environmental gradient remain unclear. In this study, we conducted a transect survey of 12 communities to address foliar nitrogen (N) and phosphorus (P) resorption strategies of four functional groups along an eastward increasing precipitation gradient in northern Tibetan Changtang Plateau. Soil nutrient availability, leaf nutrient concentration, and N:P ratio in green leaves ([N:P]_g) were linearly correlated with precipitation. Nitrogen resorption efficiency decreased, whereas phosphorus resorption efficiency except for sedge increased with increasing precipitation, indicating a greater nutrient conservation in nutrient‐poor environment. The surveyed alpine plants except for legume had obviously higher N and P resorption efficiencies than the world mean levels. Legumes had higher N concentrations in green and senesced leaves, but lowest resorption efficiency than nonlegumes. Sedge species had much lower P concentration in senesced leaves but highest P resorption efficiency, suggesting highly competitive P conservation. Leaf nutrient resorption efficiencies of N and P were largely controlled by soil and plant nutrient, and indirectly regulated by precipitation. Nutrient resorption efficiencies were more determined by soil nutrient availability, while resorption proficiencies were more controlled by leaf nutrient and N:P of green leaves. Overall, our results suggest strong internal nutrient cycling through foliar nutrient resorption in the alpine nutrient‐poor ecosystems on the Plateau. The patterns of soil nutrient availability and resorption also imply a transit from more N limitation in the west to a more P limitation in the east Changtang. Our findings offer insights into understanding nutrient conservation strategy in the precipitation and its derived soil nutrient availability gradient.     

SLC38A9: A lysosomal amino acid transporter at the core of the amino acid-sensing machinery that controls MTORC1

The mechanistic target of rapamycin (serine/threonine kinase) complex 1 (MTORC1) acts as a crucial regulator of cellular metabolism by integrating growth factor presence, energy and nutrient availability to coordinate anabolic and catabolic processes, and controls cell growth and proliferation. Amino acids are critical for MTORC1 activation, but the molecular mechanisms involved in sensing their presence are just beginning to be understood. We recently reported that the previously uncharacterized amino acid transporter SLC38A9 is a member of the lysosomal sensing machinery that signals amino acid availability to MTORC1. SLC38A9 is the first component of this complex shown to physically engage amino acids, suggesting a role at the core of the amino acid-sensing mechanism.     

Regulation of the mTOR complex 1 pathway by nutrients, growth factors, and stress

The large serine/threonine protein kinase mTOR regulates cellular and organismal homeostasis by coordinating anabolic and catabolic processes with nutrient, energy, and oxygen availability and growth factor signaling. Cells and organisms experience a wide variety of insults that perturb the homeostatic systems governed by mTOR and therefore require appropriate stress responses to allow cells to continue to function. Stress can manifest from an excess or lack of upstream signals or as a result of genetic perturbations in upstream effectors of the pathway. mTOR nucleates two large protein complexes that are important nodes in the pathways that help buffer cells from stresses, and are implicated in the progression of stress-associated phenotypes and diseases, such as aging, tumorigenesis, and diabetes. This review focuses on the key components of the mTOR complex 1 pathway and on how various stresses impinge upon them.     

Autophagy regulation by nutrient signaling

The ability of cells to respond to changes in nutrient availability is essential for the maintenance of metabolic homeostasis and viability. One of the key cellular responses to nutrient withdrawal is the upregulation of autophagy. Recently, there has been a rapid expansion in our knowledge of the molecular mechanisms involved in the regulation of mammalian autophagy induction in response to depletion of key nutrients. Intracellular amino acids, ATP, and oxygen levels are intimately tied to the cellular balance of anabolic and catabolic processes. Signaling from key nutrient-sensitive kinases mTORC1 and AMP-activated protein kinase (AMPK) is essential for the nutrient sensing of the autophagy pathway. Recent advances have shown that the nutrient status of the cell is largely passed on to the autophagic machinery through the coordinated regulation of the ULK and VPS34 kinase complexes. Identification of extensive crosstalk and feedback loops converging on the regulation of ULK and VPS34 can be attributed to the importance of these kinases in autophagy induction and maintaining cellular homeostasis.     

Nutrient limitation and morphological plasticity of the carnivorous pitcher plant Sarracenia purpurea in contrasting wetland environments

* Plasticity of leaf nutrient content and morphology, and macronutrient limitation were examined in the northern pitcher plant, Sarracenia purpurea subsp. purpurea, in relation to soil nutrient availability in an open, neutral pH fen and a shady, acidic ombrotrophic bog, over 2 yr following reciprocal transplantation of S. purpurea between the wetlands. * In both wetlands, plants were limited by nitrogen (N) but not phosphorus (P) (N content < 2% DW(-1), N : P < 14) but photosynthetic quantum yields were high (F(V)/F(M) > 0.79). Despite carnivory, leaf N content correlated with dissolved N availability to plant roots (leaf N vs , r(2) = 0.344, P < 0.0001); carnivorous N acquisition did not apparently overcome N limitation. * Following transplantation, N content and leaf morphological traits changed in new leaves to become more similar to plants in the new environment, reflecting wetland nutrient availability. Changes in leaf morphology were faster when plants were transplanted from fen to bog than from bog to fen, possibly reflecting a more stressful environment in the bog. * Morphological plasticity observed in response to changes in nutrient supply to the roots in natural habitats complements previous observations of morphological changes with experimental nutrient addition to pitchers.     

Relationship between the Relative Limitation and Resorption Efficiency of Nitrogen vs Phosphorus in Woody Plants

Most previous studies have ascribed variations in the resorption of a certain plant nutrient to its corresponding environmental availability or level in tissues, regardless of the other nutrients’ status. However, given that plant growth relies on both sufficient and balanced nutrient supply, the nutrient resorption process should not only be related to the absolute nutrient status, but also be regulated by the relative limitation of the nutrient. Here, based on a global woody-plants dataset from literature, we test the hypothesis that plants resorb proportionately more nitrogen (or phosphorus) when they are nitrogen (or phosphorus) limited, or similar proportions of nitrogen (N) and phosphorus (P) when co-limited by both nutrients (the relative resorption hypothesis). Using the N:P ratio in green foliage as an indicator of nutrient limitation, we found an inverse relationship between the difference in the proportionate resorption of N vs P and this foliar N:P ratio, consistent across species, growth-forms, and vegetation-types globally. Moreover, according to the relative resorption hypothesis, communities with higher/lower foliar N:P (more likely P/N limited) tend to produce litter with disproportionately higher/lower N:P, causing a worsening status of P/N availability; this positive feedback may somehow be counteracted by several negative-feedback mechanisms. Compared to N, P generally shows higher variability in resorption efficiency (proportion resorbed), and higher resorption sensitivity to nutrient availability, implying that the resorption of P seems more important for plant nutrient conservation and N:P stoichiometry. Our findings elucidate the nutrient limitation effects on resorption efficiency in woody plants at the global scale, and thus can improve the understanding of nutrient resorption process in plants. This study also suggests the importance of the foliar N:P ratio as a key parameter for biogeochemical modeling, and the relative resorption hypothesis used to deduce the critical (optimal) N:P ratio for a specific plant community.     

Constraint on woody cover in relation to nutrient content of soils in western southern Africa

The influence of soil nutrients on woody plants is poorly understood. Are trees – fire and other disturbance factors being equal – generally promoted by nutrient‐rich or by nutrient‐poor soils? To determine the edaphic parameters controlling woody cover, we sampled soils and summed the extent of the crowns of trees and tall shrubs on 364 plots at 20 sites in Namibia and adjacent South Africa, ranging from desert lichen‐fields to caesalpiniaceous woodland with associated mean annual rainfall of 11 mm to 535 mm. Our analysis included the macro‐nutrients N, P, Mg, K and Ca and the trace elements Mn, Fe, Cu and Zn. A boundary line analysis showed that woody cover was densest, with the greatest large‐scale heterogeneity, at intermediate nutrient contents, but consistently constrained at extreme nutrient richness as well as poverty. If aridity exerted the ultimate constraint at extreme nutrient richness, no such correlation with climate apparently applies at extreme nutrient poverty, where our graphs show an ‘oligotrophic decline’. Notwithstanding the importance of water, we suggest that extreme nutrient richness and poverty both favour grasses over tree seedlings. This is because catabolic dystrophy – a regime in which the supply of catabolic nutrients shortfalls their demand – is unlikely in environments where nutrient richness allows catabolic rates to match anabolic rates or where nutrient poverty constrains anabolic rates. We also reason that surpluses of photosynthate resulting from dystrophy can be allocated to lignin and that the potential for woody growth thus corresponds to soils of intermediate nutrient content. This explains why woody cover is consistently but not homogeneously densest in nutritionally intermediate plots in our dataset. Hence, the abundance of woody plants in various biomes may be determined partly by soil nutrient content, particularly of Cu, Zn, and other elements indispensible for catabolism.     

TOR inhibition primes immunity and pathogen resistance in tomato in a salicylic acid-dependent manner

All organisms need to sense and process information about the availability of nutrients, energy status, and environmental cues to determine the best time for growth and development. The conserved target of rapamycin (TOR) protein kinase has a central role in sensing and perceiving nutritional information. TOR connects environmental information about nutrient availability to developmental and metabolic processes to maintain cellular homeostasis. Under favourable energy conditions, TOR is activated and promotes anabolic processes such as cell division, while suppressing catabolic processes. Conversely, when nutrients are limited or environmental stresses are present, TOR is inactivated, and catabolic processes are promoted. Given the central role of TOR in regulating metabolism, several previous works have examined whether TOR is wired to plant defence. To date, the mechanisms by which TOR influences plant defence are not entirely clear. Here, we addressed this question by testing the effect of inhibiting TOR on immunity and pathogen resistance in tomato. Examining which hormonal defence pathways are influenced by TOR, we show that tomato immune responses and disease resistance to several pathogens increase on TOR inhibition, and that TOR inhibition-mediated resistance probably requires a functional salicylic acid, but not jasmonic acid, pathway. Our results support the notion that TOR is a master regulator of the development–defence switch in plants.     

Compositional profiles of Rhodosporidium toruloides cells under nutrient limitation

Lipid production by the red yeast Rhodosporidium toruloides was explored under nutrient limitation. To determine the compositional profiles of R. toruloides cells, samples were prepared using a continuous cultivation process under nutrient limitation and analyzed via several methods, including Fourier transform infrared spectroscopy and elemental analysis. Under nitrogen limitation, as the dilution rate increased, the cellular lipid content decreased but the carbohydrate and protein contents increased. Under carbon limitation, the cellular lipid, protein, and carbohydrate contents remained relatively constant at the different dilution rates. Moreover, the cellular elemental composition was essentially identical under nitrogen and carbon limitation at a high dilution rate of 0.20 h⁻¹. We also analyzed the consumed carbon to nitrogen (C/N) under different nutrition conditions. The results indicated that the consumed C/N had a major influence on cell metabolism and product formation, which contributed to our understanding of the physiological characteristics of R. toruloides.

     

Temperature Affects Stoichiometry and Biochemical Composition of Escherichia coli

Temperature is a master variable controlling biochemical processes in organisms, and its effects are manifested on many organizational levels in organisms and ecosystems. We examined the effects of temperature on the biochemical composition and stoichiometry of a model heterotrophic bacterium, Escherichia coli K-12, held at constant growth rate in chemostats. Increasing temperature led to increased cellular organic carbon (C) and organic nitrogen (N) with decreased phosphorus (P) content, leading to increased C/P and N/P biomass ratios. P content was related to cellular RNA, which is P-rich (9–10% by weight) and nonnucleic acid P (presumably composed of mostly phospholipids, intracellular phosphate, and polyphosphate). These results indicate that E. coli allocates an increased proportion of its P cell quota toward assembly (ribosomes) at low temperatures and an increasing proportion toward resource acquisition machinery (membranes) at higher temperatures. If these results are relevant to the behavior of prokaryotic heterotrophs in natural settings (the gut, soils, lakes, oceans, etc.), it suggests greater nutrient regeneration and less microbial nutrient retention as temperatures increase.     

Taxonomic and regional patterns in benthic macroinvertebrate elemental composition in streams

1. Ecological stoichiometry has been used to better understand dynamics in consumer growth and the role of consumer‐recycled nutrients because it focuses on more than one element. Most research has focused on pelagic rather than benthic consumers. Variation in elemental composition among benthic consumer taxa would suggest that taxa differ in their susceptibility to nutrient limitation or in their role in recycling nutrients. 2. We collected benthic macroinvertebrates from streams in two regions (Indiana–Michigan and Wisconsin, U.S.A.) to examine taxonomic and regional variation in benthic macroinvertebrate body carbon (C), nitrogen (N), and phosphorus (P) concentrations and ratios. 3. Elemental composition varied little within taxa common to both regions. In contrast, elemental composition differed greatly among taxa and appeared to be related to phylogeny. The elemental composition of macroinvertebrates clustered into three distinct groups: insects, mollusks, and crustaceans. To a lesser extent, insects and mollusks also differed in elemental composition among genera. 4. Functional feeding groups (FFGs) differed in elemental composition, with predators having a higher N content than other groups. Substantial elemental imbalances between C and N were found between most primary consumers and their likely food sources, and the magnitude of the imbalance depended in part on the FFG. 5. Our results support an assumption of most ecological stoichiometry models that, within a species, the elemental composition of aquatic invertebrates is relatively constant. Variation in elemental composition among taxa at various higher taxonomic levels suggests that susceptibility of stream invertebrates to nutrient limitation and their role in nutrient cycling will strongly depend on phylogeny.     

Bumble bees selectively use native and exotic species to maintain nutritional intake across highly variable and invaded local floral resource pools

1. Changes to plant community composition after invasion are well documented but how these shifts directly affect higher trophic levels is still poorly understood. One potentially important factor is the change in nutritional availability after an invasion. Shifts in nutrient availability could affect the nutrient intake of organisms that live in invaded habitats, causing reduced fecundity and survival. 2. The effects of the interaction among nutrient availability, selection, and diet on nutrient intake of a native bumble bee were examined. No nutritional differences were found between exotic and native pollen or collected and non‐collected pollen in protein or amino acid content, suggesting that differences in nutrient intake from random are based on selection. 3. Nutrient intake was simulated when pollen was selected randomly across all available plant species and when selection was restricted to native plants only or exotic plants only using a permutation model and compared with observed collection. The results suggest that pollen collection is non‐random and that selecting only native or exotic plants cannot provide the protein or amino acid intake observed. 4. These results may help to explain why the responses of native bees to exotic plants are so variable. If the exotic plants in a community can supply the necessary nutrients, bees may readily incorporate them into their diets, but if not, exotic plants may be avoided.     

Biochemical compositions of two dominant bloom- forming species isolated from the Yangtze River Estuary in response to different nutrient conditions

Variations of cellular total lipid, total carbohydrate and total protein content of two dominant bloom-forming species (Skeletonema costatum and Prorocentrum donghaiense) isolated from the Yangtze River Estuary were examined under six different nutrient conditions in batch cultures. Daily samples were collected to estimate the cell growth, nutrient concentration and three biochemical compositions content during 7 days for S. costatum and the same sampling procedure was done every other day during 10 days for P. donghaiense. Results showed that for S. costatum, cellular total lipid content increased under phosphorus (P) limitation, but not for nitrogen (N) limitation; cellular carbohydrate were accumulated under both N and P limitation; cellular total protein content of low nutrient concentration treatments were significantly lower than that of high nutrient concentration treatments. For P. donghaiense, both cellular total lipid content and total carbohydrate content were greatly elevated as a result of N and P exhaustion, but cellular total protein content had no significant changes under nutrient limitation. In addition, the capability of accumulation of three biochemical constituents of P. donghaiense was much stronger than that of S. costatum. Pearson correlation showed that for both species, the biochemical composition of three constituents (lipid, carbohydrate and protein) had no significant relationship with extracellular N concentration, but had positive correlation with extracellular and intracellular P concentration. The capability of two species to accumulate cellular total lipid and carbohydrate under nutrient limitation may help them accommodate the fluctuating nutrient condition of the Yangtze River Estuary. The different responses of two species of cellular biochemical compositions content under different nutrient conditions may provide some evidence to explain the temporal characteristic of blooms caused by two species in the Yangtze River Estuary.